Production of artificial filaments



July 14, 1936 H. DREYFUS PRODUCTION OF ARTIFICIAL FILAMENTS Filed March22, 1933 INVE/V TU/Q Patented July 14, 1936 Henry Dreyfus, London,England Application March 22, 1933, Serial No. 662,049

In Great Britain April 30, 1932 6 Claims.

This invention relates to the production of artificial filaments or thelike by the extrusion of a spinning solution into an evaporativeatmosphere, as for example by the extrusion of a spinning solutioncontaining cellulose acetate or other cellulose derivative in a volatilesolvent liquid. Examples of other cellulose derivatives which may bespun by this method are other cellulose esters, such as celluloseformate, propionate and butyrate, and cellulose ethers, such as ethyland benzyl cellulose.

The invention is concerned with the heating of the spinning solutionprior to its extrusion, the object of the invention being to employ agaseous medium for the purpose of applying heat to the spinningsolution.

In the dry or evaporative method of spinning, a spinning jet is arrangedin a spinning cell, the cell being provided with means for bringingtheevaporative medium, usually air, within the cell to the requiredtemperature to bring about setting of the filaments. This air is usuallycaused to flow in a counter-current direction to the filaments, that is,the air enters at or near an end of the cell remote from thejet, and isdrawn from suction applied at the outlet for the air. The

fiow of air removes the volatile solvent from the filaments, solventvapours being carried from the cell together with the air by the appliedsuction.

The spinning solution is led to the jet by a pipe connected to a pump,usually outside the cell, this pipe being in the neighbourhood of theoutlet of the air from the cell, and so under the influence of thetemperature of this air. Generally the pipe is constituted by a filterimmediately connected to the jet, and the relatively slow passage of thespinning solution through the filter increases the opportunity for thesolution to be influenced by the surrounding air.

U. S. Patent No. 1,814,468 describes the use of collector devices bymeans of which the air may be constrained into the immediate vicinity ofthe jet and shows forms of collector devices which serve as jackets todirect such constrained air to pass into close proximity with the filterbefore being exhausted from the cell. In this way the heating effect ofthe air which is withdrawn can be utilized to increase the temperatureof the spinning solution on its way to the jet.

According to the present invention, use is also made of the heatedatmosphere for the attemperation of the spinning solution, the featureof the invention being that the atmosphere is carried through the bodyof the spinning solution in the Two forms of apparatus according to theinvention are shown in the accompanying drawing as. applied to thedownward spinning of filaments into an upward current of air.

In the drawing:- Figure l is a sectional view of a spinning cellcontaining a filter provided with passages for-the interior circulationof air; and.

Figure 2 is a sectional view of a jet fitting comprising a supply. pipearranged for internal and external heating.

Referring to Figure l, a filter body 3 carried by the supply pipe 4 isprovided with a central pas sage 5 communicating by a number of.passages B with the outside of the body. A casing I is secured aboutthe body 3 so as to form an annular space 8 into which the spinningsolution fiows after passing through the filter material 9 covering theouter perforated wall ll) of the body3.

An annular jet 1 I is secured to the lower end of the members 3, l, thepassage 5 inside the member 3 thus being in communication with theinterior of the spinning cell I2 through the centre of the jet ll.

Air is withdrawn from the cell l2 in controlled amount by the draw-01fI3, some of the air passing through the passage 5 while the remaindertravels outside the casing I. A plate I 4 surrounding the casing 1except for a gap l5 may be used to cause the external air to come intoclose contact with the casing l, and by suitably adjusting the size ofthe gap I5 to the total area of the passages 6, the relative amounts ofexternal and internal air may be regulated. It will be readily seen thatin addition to air being constrained into the immediate vicinity of thespinning orifices, as claimed in U. S. Patent No. 1,814,468, the air isalso caused to heat up the spinning solution on its way to the jet.

If desired, shields I6 may be arranged over the heating pipes ll in thecell l2 to assist in directing the stream of air induced by convectionto the outside of the filter body. The spinning solution entering themember 3 is thus given a preliminary heating by the somewhat cooler airwhich passes from the extrusion zone into the passage 5 and is thenheated to a greater degree by the hotter air after it has passed fromthe inside of the filter body to the annular space 8 inside the casing1.

Referring now to Figure 2, a disc-type jet I8 is carried by the lowerend of a supply pipe l9 which is enlarged as shown at 20 to enable apipe 2| to be carried centrally therethrough. This pipe 2| communicateswith the outside of the pipe H) by passages 22 and also with a drawoifpipe 23 by a connecting pipe 24. Air can thus be drawn through the pipe2| while the spinning solution fiows through the annular space 25between the pipe 2! and the outside of the pipe 20.

Instead of the air passing directly into the passages 22, it may beconstrained to pass first through a jacket 26 surounding the pipe 20 andmay be caused to pass along the whole length of the jacket by arrangingthe inlet holes 2'! at the end of the jacket remote from the passages22. In this way, the spinning solution is not only surrounded by theheated air but has a current of air passing internally through it.

All the air may be withdrawn by the pipe 23 and thus utilized forheating the spinning solution, or part of the air may be withdrawn by asecond draw-01f pipe 28 so that the heating efiect may be regulated byadjusting the proportions of the air passing through the two pipes.

The zone into which the spinning solution is extruded by the jet l8 maybe cooled by the injection of a suitable quantity of cool air, as bymeans of the flattened pipe 29.

What I claim and desire to secure by Letters Patent is:-

1. In the spinning of artificial filaments or the like by the extrusionof a spinning solution into a heated evaporative atmosphere, the stepsof filtering the solution before extrusion, and passing evaporativeatmosphere internally and externally of the body of. the spinningsolution while it is being filtered so as to attemperate the solutionprior to extrusion.

2. Process for the production of artificial filaments or the like, saidprocess comprising filtering a spinning solution, extruding saidsolution downwardly into an upward current of heated evaporativeatmosphere, and passing evaporative atmosphere from said currentinternally and externally of the body of the solution while it is beingfiltered so as to attemperate the solution prior to extrusion.

3. Apparatus for the extrusion of spinning solutions into an evaporativeatmosphere, said apparatus comprising a supply pipe adapted to conductthe solution towards the point of extrusion, a passage runninginternally of said pipe and communicating with the exterior thereof, anda jacket surounding said pipe, said jacket communicating with theinternal passage, and means for drawing evaporative atmosphere throughthe jacket and internal passage so as to attemperate the solutionpassing through the supply pipe.

4. Apparatus for the extrusion of spinning solutions into an evaporativeatmosphere, said apparatus comprising a spinning cell, a jet in saidcell, a supply pipe adapted to conduct spinning solution to said jet, apassage running internally of said pipe and in communication with theinterior of said cell, means for drawing evaporative medium through saidcell both externally of said supply pipe and internally via saidpassage, and means for constraining the evaporative medium drawnexternally of the pipe to pass in close proximity thereto.

5. Apparatus for the extrusion of spinning solutions into an evaporativeatmosphere, said apparatus comprising a spinning cell, a jet in saidcell, a supply pipe adapted to conduct spinning solution to said jet, apassage running internally of said pipe and in communication with theinterior of said cell, means for drawing some evaporative atmospherefrom said cell through said internal passage, and means for drawingother evaporative atmosphere externally of the supply pipe.

6. Apparatus for the extrusion of spinning solutions into an evaporativeatmosphere, comprising a spinning cell, a jet in said cell, a filter incommunication with the jet, a passage running internally of said filterand in communication with the interior of the cell and forming anannular filtering zone surrounding said passage, means for drawingevaporative medium both externally of said filter and internally viasaid passage, and means for constraining the evaporative medium drawnexternally of the filter to pass in close proximity thereto.

HENRY DREYFUS.

